Edge preservation for spatially varying power conservation

ABSTRACT

Described herein are systems and methods that reduce power consumption for an electronics device that includes a display. The systems and methods generate edge detection video information for a graphics component that allows a person to visually identify and locate the graphics component within a display area for the display device. Video information in the display area other than the edge detection video information is altered to conserve power. Preserving the edge detection video information for the window maintains a person&#39;s ability to see and locate the window at a later time, even though other portions of the display area have been altered and potentially visually degraded to conserver power.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part and claims priority under 35U.S.C. §120 from commonly-owned and co-pending U.S. patent applicationSer. No. 10/891,734, filed Jul. 15, 2004 and titled “SPATIAL-BASED POWERSAVINGS”, which claimed priority under 35 U.S.C. §119(e) from U.S.Provisional Patent Application No. 60/487,761 filed on Jul. 16, 2003;each of these applications is incorporated herein by reference for allpurposes.

FIELD OF THE INVENTION

This invention relates to systems and methods that reduce power consumedby an electronics device including a display. More particularly, thepresent invention relates to techniques for conserving power by alteringvideo information for portions of a display area while preserving edgedetection information for a graphics component.

BACKGROUND OF THE INVENTION

Video output consumes a significant amount of power for a laptop ordesktop computer. Other computing systems and electronics devices—suchas handheld computing devices, cellular telephones and musicplayers—also devote a large fraction of their power budget to video.Power consumption sensitivity increases for portable devices that relyon a battery having limited energy supply.

Currently, commercially available power conservation techniques alter anentire image at once. Most techniques uniformly shut down a display orunvaryingly modify all video output in an image after some predeterminedtime. These techniques usually impede a person's ability to see graphicsitems and further use the computing device. Frequently, a personresponds by reactivating the entire display—at full power. As a result,little power is saved.

SUMMARY OF THE INVENTION

The present invention provides systems and methods that reduce powerconsumption for an electronics device that includes a display. Thesystems and methods generate edge detection video information for agraphics component that allows a person to visually identify and locatethe graphics component within a display area for the display device.Video information in the display area other than the edge detectionvideo information is altered to conserve power. Preserving the edgedetection video information for the window maintains a person's abilityto see and locate the window at a later time, even though other portionsof the display area have been altered and potentially visually degradedto conserver power.

Generating edge detection video information in a display area mayinclude edge designation logic and one or more edge detection algorithmsthat determine what video information to preserve to maintain a person'sability to see and locate a graphics component. Edge detection videoinformation may be generated for multiple graphics components, dependingon video output in the display area.

Since the edge detection video information occupies a minor percentageof the display area (e.g., on a pixel basis), avoiding or minimizingpower conservation video alterations for these relatively small portionsdoes not contribute largely to power consumption—but maintains aperson's ability to subsequently locate and return to using a graphicscomponent and display area. This also permits more aggressive powerconserving alterations to other video information in the display area.

In one aspect, the present invention relates to a method for reducingpower consumed by an electronics device that includes a display device.The method includes generating edge detection video information for agraphics component that allows a person to visually locate the graphicscomponent in a display area for the display device. The method alsoincludes altering video information in the display area, other than theedge detection video information; to produce altered video information,such that the display device will consume less power when displaying thealtered video information than an amount of power that would be requiredto display the video information without the alteration. The methodfurther includes displaying the altered video information with the edgedetection video information.

In another aspect, the present invention relates to a method forreducing power consumed by an electronics device. The method includesgenerating edge detection video information for a graphics component.The method also includes monitoring user activity, and after a thresholdinactivity time, altering video information in the display area otherthan the edge detection video information.

In yet another aspect, the present invention relates to a computerreadable medium including instructions for reducing power consumed by anelectronics device that includes a display device.

These and other features of the present invention will be presented inmore detail in the following detailed description of the invention andthe associated figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates video information output on a display devicesuitable for use with a laptop computer or desktop computer inaccordance with one embodiment of the present invention.

FIG. 1B illustrates the display device of FIG. 1A after videoinformation alteration and edge detection video information preservationfor multiple graphics components in accordance with a specificembodiment of the present invention.

FIG. 1C illustrates a video output for a handheld computer device inaccordance with one embodiment of the present invention.

FIG. 1D illustrates video output for the handheld device of FIG. 1Cafter video information alteration and edge detection video informationpreservation in accordance with a specific embodiment of the presentinvention.

FIG. 2 demonstrates a visual information reduction mechanism employed bythe human vision system that allows a person to recognize objects basededge information and shape.

FIG. 3 shows video information alteration for an exemplary pixel for anLCD device to conserve power in accordance with one embodiment of thepresent invention.

FIG. 4A illustrates a process flow for reducing power consumed by adisplay device in accordance with one embodiment of the invention.

FIG. 4B illustrates a process flow that monitors user inactivity beforereducing power consumed by a display device in accordance with anotherembodiment of the invention.

FIG. 5 illustrates an exemplary computer system suitable forimplementing the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described in detail with reference toa few preferred embodiments thereof as illustrated in the accompanyingdrawings. In the following description, numerous specific details areset forth in order to provide a thorough understanding of the presentinvention. It will be apparent, however, to one skilled in the art, thatthe present invention may be practiced without some or all of thesespecific details. In other instances, well known process steps and/orstructures have not been described in detail in order to notunnecessarily obscure the present invention.

Power conservation methods and systems described herein generate andpreserve edge detection video information for a graphics component,which allows a person to visually identify and locate the graphicscomponent in a display area for the display device after alterations tovideo information other than the edge detection video information. Videoinformation other than the edge detection video information is alteredsuch that the alteration decreases power consumption for a displaydevice or an electronics device. Often, these power conservationalterations degrade visual quality and/or perceptibility of the alteredvideo information. Meanwhile, the edge detection video information maybe left untouched and unaltered. In another embodiment, the edgedetection video information is also altered to decrease powerconsumption, albeit to a lesser extent or rate. In either case, thepresent invention preserves a person's ability to see and detect theedge detection video information (and the associated graphics component)at a later time when information around the edge detection videoinformation has been altered.

For example, a person may stop using a handheld or laptop computer forsome time. The present invention generates edge detection videoinformation for a graphics component whose usage may be relevant to aperson when the person returns to using the device. For example, thegraphics component may correspond to a window or program that a personwas last using before inactivity in the display area began. The edgedetection video information for the window is then at least partiallypreserved so as to not degrade a person's ability to detect thewindow—while other video information in the display area is altered toconserve power. This may be done for multiple graphics components.

The video information other than the edge detection video information isaltered at some time (e.g., due to inactivity in the display area)according to power conservation system design. This may includedecreasing the brightness and luminance, altering color, turninginactive video information to black, etc. Several suitable alterationsto conserve power are described below. Power conservation systemdesigners and/or users may also vary the rate of video informationalterations and/or set a lower limit for alterations and videoinformation presentation. Alteration may occur once, multiple times, orcontinuously according to power conservation control. Often, alterationproduces or progresses to a state where the video information other thanthe edge detection video information is significantly visiblydegraded—or even unrecognizable. For example, luminance for the videoinformation other than the edge detection video information may bereduced to black, or some minor fraction of its original luminancelevel, that compromises visual processing and recognition. In anotherembodiment, the present invention alters edge detection videoinformation, albeit to a lesser extent. For example, edge detectionvideo information may be altered at a slower rate and less aggressivelythan alterations the background and graphics components.

The amount of power conserved will depend on the display device. OLEDdevices are current driven devices where electrical current flow toindividual pixel elements varies with light output and video informationfor each pixel. Reducing RGB values for each pixel (or luminance, whichthen reduces RGB values) draws less current on a pixel-by-pixel basis.For many LCD devices, perceived luminance at each pixel of the LCD is acombination of backlight level and transmissivity of the videoinformation using pixilated filters. To reduce power, one may altervideo information so as to reduce transmissivity to the point where alower backlight level may be used when displaying lower luminance videoinformation. Hardware power consumption and conservation is described infurther detail below

When the person returns to the display, even though video informationother than the edge detection video information has been altered anddegraded (and corresponding power savings achieved), the user may stillreadily detect and locate the preserved edge detection video informationand use it to readily return to usage of a graphics component andelectronics device without any intermediate steps or without activatingthe entire display, e.g., just to find a window or icon. The presentinvention thus preserves the person's ability to detect and locate agraphics component and maintains their ability to quickly return tousage of the device after video information has been altered anddegraded to conserve power. This also avoids annoyance by users thatprefer to be able to see some active video at any time, informs a userthat a computer has not entered a hibernate mode when it has not (entirescreen shut-downs are often confused as a hibernate mode, verynoticeable in their sudden luminance change, and commonly cause a userto re-activate the entire display to avoid entering the hibernate mode),and preserves visual perception for portions of a display area that aretypically returned to after inactivity, such as graphics components andprograms used before the inactivity began.

Some embodiments alter the edge detection video information in additionto altering video information other than the edge detection videoinformation. In this case, the edge detection video information isaltered less aggressively. This preferential treatment allows a user tosubsequently identify the window with visual salience and recognitionrelatively greater than the remainder of video information in thedisplay area.

The present invention finds use with a wide array of display devices andelectronics devices. For example, desktop and laptop computers with12-20″ display areas, measured diagonally, are now common and maybenefit from techniques described herein. The present invention isparticularly useful for portable electronics devices powered from abattery or other limited source of energy. Video conservation techniquesdescribed herein may significantly extend battery longevity and useabletime for the portable electronics device.

FIG. 1A illustrates video information output on a display device 40suitable for use with a laptop computer or desktop computer. While thepresent invention will now be described as video information, graphicscomponents and hardware components, those skilled in the art willrecognize that the subsequent description may also illustrate methodsand discrete actions for reducing power consumption for a display deviceand associated electronics device.

Display device 40 displays video information, and may include a liquidcrystal display (LCD) device, projector, or an organic light emittingdiode (OLED) device. Other display devices and technologies are suitablefor use with the present invention.

Display device 40 outputs video information for a laptop or desktopcomputer within a display area 44. Display area 44 refers to a currentimage size of a display device. Pixel dimensions may characterize thesize of display area 44. Physical dimensions (e.g., inches) that span animage produced by the display device may also characterize the size ofdisplay area 44. The display area 44 may be less than a maximum displayarea for the device, e.g., when a user manually alters horizontal andvertical expansion of a CRT image. Linear dimensions for display area 44output by a projector will vary with the distance between the receivingsurface and projector output lens and a splay angle for the projector.The physical dimensions may be measured on the projected image, usuallyafter any keystone distortion has been suitably corrected for, which mayalso decrease the display area relative to the maximum display area. Tofacilitate discussion of LCD based power savings, device 40 will also bereferred to as an LCD 40.

An electronics device, such as a desktop, laptop or handheld computer,often runs a graphics-based user interface 42. The graphics-based userinterface 42 facilitates interaction between a user and the laptopcomputer and/or between the user and one or more programs run on thecomputer. Several suitable graphics-based user interfaces 42 are wellknown and commercially available, such as those provided by Microsoft ofRedmond, Wash., and Apple Computer of Cupertino, Calif., for example.Interface 42 also controls video information output on LCD 40.

The video information refers to data for display using the displaydevice 40 to produce a visual representation of some form. The videoinformation data is typically stored in a logical manner using valuesassigned to pixel locations. The pixel locations may correspond to apixel arrangement used for display device 40 or an arrangement used forstoring the data. Exemplary color schemes suitable for assigning valuesto video information are described below. Stored video information mayinclude a resolution that may or may not match a resolution for displaydevice 40. For example, picture video information used for background 48may be stored as a bitmap having a resolution that does not match theresolution of LCD 40. Background 48 represents a backdrop graphics itemfor graphics-based user interface 42, and may include a picture, singlecolor or other backdrop graphics.

The video information in display area 44 includes one or more graphicscomponents. A graphics component refers to a discrete visual objectoutput by display device 40. A wide variety of graphics components aresuitable for video information preservation as described herein, and thepresent invention is not limited to any particular graphics component.Icons 41 are a popular graphics component that each corresponds to aparticular program; selecting an icon 41 allows a user to initiate aprogram offered on the electronics device. Toolbar 43 is anothergraphics component that offers a visual tool for graphics-based userinterface 42. Toolbar 43 includes a number of its own graphicscomponents, such as toggles 43 a-43 b and a clock, to help a userinteract with the electronics device and programs provided thereon.

Windows 45 and 47 are graphics components and output video informationrelated to a program running on the computer. Common programs includeword processing programs, file navigation displays, Internet Browsers,drawing programs, music player programs, and video games, for example.For FIG. 1A, window 45 provides video information for a word processingprogram, while window 47 provides video information for a filenavigation program. Other programs are known in the art and the presentinvention is not limited by any particular graphics-based user interface42 or program run therewith. Windows 45 and 47 may each include theirown bitmap comprising an array of pixel values. Rectangular windows arecommon and vary in size from a maximum size that roughly spans a displayarea 44 to smaller sizes within display area 44. Windows 45 and 47 mayalso be operated in minimized states where the program is active but thewindow is not visible. A toggle 43 a or 43 b on toolbar 43 allowsswitching between these states.

Windows 45 and 47, icons 41, toolbar 43, and toggles 43 a and 43 b, eachinclude an edge portion and an internal portion. For example, window 45includes an edge portion 45 a and an internal portion 45 b that includessample word processing text, while window 47 includes an edge portion 47a and an internal portion 47 b that includes several depictions of filesand folders. For a window, the internal portion often includes a mainwork area for user input. For example, a window that outputs videoinformation for a drawing program may include a border portion and aninternal main work area, which usually displays a white backing thatwill consume maximal power when displayed.

The present invention discriminates what video information is altered indisplay area 44 (and for each graphics component) to preserve perceptionof each graphics component. In one embodiment, power conservationpreserves edge detection video information for one or more graphicscomponents. In another embodiment, power conservation minimizes visualimpact of alterations to edge detection video information for eachgraphics component.

As the term is used herein, edge detection video information refers tovideo information that allows a user to identify the graphics componentbased on edge and/or shape detection, or is otherwise useful for visualrecognition of the graphics component in a display area. The edgedetection video information may be more noticeable when videoinformation other than the edge detection video information has beenaltered or degraded to conserve power. In one embodiment, the edgedetection video information includes perimeter video information in aborder portion of the window, and allows a user to identify the windowbased on shape detection.

Generally, human perception of visual information is a combination ofthe physical composition of a light beam (spectral composition,intensity, etc.), physiological processes in the human eye,physiological processes in the optic nerves as a consequence of lightstimulus in the eye, and processing of these optic stimuli in the brain.

Human vision employs a number of processing and information reductionmechanisms that convert light and potentially tremendous amounts ofambient visual information into a manageable biochemical signal. Themain information reduction mechanisms include: edge detection, shapedetection, motion detection, and foreground/background separation.Foreground/background separation divides an environment to into aforeground where relatively more information is processed (e.g. allowsmore detail, such as looking closely at an insect in hand) and abackground where less information is processed (e.g. provides lessdetail, such as the ambient room). Motion detection reduces detail formoving objects to allow motion processing (e.g., watching the insect flythrough a room, albeit at lower detail than when in hand). Edgedetection converts continuous color and luminance information or objectsinto lines (e.g., converting a uniform color square into four perimeterlines). Shape detection allows a person to recognize objects usinglines, such as outer contours that resemble a shape for the object(e.g., a checkerboard based on its known arrangement of adjacentsquares). While these mechanisms are useful to reduce the large volumeof information sent to the brain at any one instance, they also createimperfections in visual perception.

In one embodiment, the present invention leverages imperfection in humanvisual processing to alter video information and reduce powerconsumption by a display device. As described above, edge and shapedetection are visual information reduction mechanisms employed by thehuman vision system that allow a person to recognize objects based onreduced information—namely, its edge patterns and shape. FIG. 2illustrates this mechanism for a simple star 31. As shown, a person'svisual system processes star 31 to produce an edge pattern 32, whiledisregarding information in internal portion 34 (commonly, adjacentvisual input of the relatively same color and luminance is disregardedby the visual processing system until a change occurs: edge detection).This first edge detection visual processing technique reduces the amountof information sent to the brain: the internal portion 34 is nottypically sent, just the edge pattern 32. Second, the brain receives asignal for the edge information 32 from visual processing and recognizesit as a ‘star’.

The present invention leverages these human processing schemes to reducethe amount of power output by display device without sacrificing theability for a user to identify and locate one or more graphicscomponent.

FIG. 1B shows the preservation of edge detection video information ofvideo information in display area 44, while luminance for videoinformation other than the edge detection video information in displayarea 44 has been reduced, in accordance with a specific embodiment ofthe present invention.

The edge detection video information may include perimeter informationand/or internal edge information. The perimeter information includesvisual boundary information that facilitates shape recognition. Theinternal edge information increases the amount of edge detection videoinformation for a graphics component and distinguishes similarly shapedgraphics components. In this case, graphics components with similarshapes may include more internal edge information to facilitatedifferentiation.

Perimeter edge detection video information has been saved for eachgraphics component in display area 44. For example, perimeter edgedetection video information 45 a resembles the shape of the rectangularword processing window 45 from FIG. 1A. In addition, as shown in FIG. 1Bby ghost outlines for each graphics component in the darkened displayarea 44, perimeter edge detection video information has also beenpreserved for icons 41, window 47, toolbar 43 and its toggle 43 a and 43b. The preserved edge detection video information allows a person toidentify and locate each graphics component based on its edgeinformation and/or shape.

Internal edge detection video information may also be used to aid indetection of each graphics component. For example, window 47 includesvarious internal file representations whose outlines are preserved todifferentiate recognition of window 47 as a file navigation window afterpower conservation begins. Other internal information may be preservedto differentiate a graphics component, and will depend on the graphicscomponent, as one of skill in the art will appreciate. As shown, edgesof upper border portions for each window 45 and 47 are also preserved tofacilitate their recognition. Other internal edge detection informationmay be preserved. FIG. 1D shows internal lines for several icons 26shown in FIG. 1C that are preserved to facilitate recognition of eachicon. In general, the present invention may preserve any internal orperimeter video information for a graphics component suitable for edgeand/or shape detection.

Power conservation alters video information in display area 44 such thatdisplay device 44 consumes less power than an amount of power requiredto display the video information without alteration. As shown, luminancefor video information in all pixels—other than the preserved edgedetection video information—has been reduced (to black in this instance,or some other near zero luminance). Additional power conservationalterations will be described in further detail below.

In one embodiment, the edge detection video information in display area44 is turned white to facilitate contrast and line recognition, whichpermits easy identification and location of each graphics componentafter any luminance decreases. In another embodiment, the edge detectionvideo information is not altered from its original colors andpresentation. Since video information in the edge detection videoinformation represents a relatively small portion of display area 44,and a likely place for subsequent user visual interaction andrecognition, pixel granularity power conservation may be slightlysacrificed for the expected demand for visual recognition of thegraphics components.

Power conservation also decreased luminance for video informationinternal to each graphics component. For example, video informationinternal to perimeter 45 a, which mainly comprises text for a wordprocessing window, includes video information not generally required forshape detection of the window. As shown, the internal portion is heavilyreduced in luminance. This reduces power consumption of this area(depending on the display device) and does not compromise the ability toidentify window 45 and its associated program based on shape. Theinternal white portion of a window often constitutes most of the surfacearea for the window. For an OLED display with pixel granularity powerconsumption, this internal alteration reduces most of the power requiredto display the window.

The present invention thus allows a user to detect and readily return tographics component usage within display area 44—by preserving edgedetection video information that constitutes a relatively smallproportion of display area 44—while reducing video output and powerconsumption from the rest of the display area 44. In contrast,conventional display devices and power conservation require the entiredisplay area to be active and consume power—or fully off. For largerdisplay areas, displaying only edge detection video information and notthe remainder of display area 44 may lead to a 70+ percent reduction inpower consumption, which is particularly valuable when the displaydevice is powered by a battery in a portable computer.

Edge detection video information may also include characteristic colorinformation in the graphics component. Detection of a graphics componentmay be enhanced using the preservation of characteristic colorinformation for the graphics component. Many graphics-based userinterfaces 42 include characteristic colors for windows, toolbars andicons, such as a color set using an appearance theme (e.g., all windowsinclude a blue, ‘rose’ or ‘teal’ color in the border portion 45 a).Correspondingly, power conservation and/or recognition of a graphicscomponent may be enhanced using color. The characteristic color allows auser to identify a graphics component based on a known, expected andconsistent color of the graphics component. In this embodiment, thepresent invention identifies characteristic color video information(perimeter and/or other) for a graphics component, preserves the colorvideo information amidst alterations to other video information in thedisplay area 44. If the characteristic color is blue for example, thenvideo information in display area 44 is reduced in luminance (and colorif present) to reduce power, while the color in the edge detection videoinformation is preserved to facilitate color-based recognition.

The edge detection video information may also include text thatdesignates the program name or file currently open. For manygraphics-based user interface 42 designs, a window 45 includes textwithin a border portion that identifies the window. For a wordprocessing window, the text may include a specific file name and programname. For a music player program, the text may include the playerprogram name. For a file navigation display, the text may include acurrent file or directory. In one embodiment, the present inventionpreserves text information that allows a user to scan an altered displayarea 44, find and read any text for a graphics component, and identify agraphics component amongst a number of similar graphics componentswithout a need for reactivating the entire display area 44.

In one embodiment, the present invention alters the edge detection videoinformation in addition to other video information in the display area44. For example, video information for the former may be altered at aslower rate and less aggressively than alterations to the background andother portions of the display area. This may be done to permit LCD basedstepwise reductions in backlight luminance as will be described below,for example.

In another embodiment, the present invention alters edge detection videoinformation such that the information is illustrated with increasedcontrast. In this case, edge detection video information may altered toincrease contrast with the neighboring video information—and/or videoinformation in background 48 that borders each edge may be altered toenhance border edge detection. For example, the edge detection videoinformation may be turned white when the video information in background48 decreases in luminance.

Power conservation techniques described herein are also well suited foruse with electronics devices other than laptop and desktop computers.Other exemplary devices include handheld computers, cellular telephones,portable music players, digital cameras, and other portable computingand electronics devices that include a video display.

FIG. 1C illustrates a handheld computer device 20 in accordance with oneembodiment of the present invention. FIG. 1D illustrates handheld device20 after video information alteration in accordance with a specificembodiment of the present invention.

Handheld computer device 20 includes a display device 22 that displaysvideo information. Individual pixel locations within a display area 23for device 22 permit allocation and addressing of video informationdisplayed within a display area 23. Pixel dimensions and resolution maycharacterize display area 23. For example, display device 22 maycomprise an OLED display device that offers pixel dimensions of 480×640.The OLED device permits video information changes for individual pixelsto affect power consumption and conservation at pixel granularity.

Handheld device 20 runs a graphics-based user interface 24 withindisplay area 23. Interface 24 facilitates interaction between a user anddevice 20 and/or between the user and one or more programs run oncomputer device 20. To do so, interface 24 outputs video information ondisplay device 20. As shown in FIG. 1C, interface 24 currently displaysa background 28 and a set of icons 26 that each correspond to a programavailable on device 20. The icons 26 are displayed on background 28,which includes its own set of background video information and providesa backdrop environment for graphics-based user interface 24. Twotoolbars 30 are output in display area: a top toolbar 30 a that includesa pull-down toggle for interface 24 and a bottom toolbar 30 b thatincludes a clock.

FIG. 1C illustrates display area 23 before alteration of videoinformation in display area 23, while FIG. 1D shows display area 23after alteration of video information. As shown in FIG. 1D, videoinformation in background 28 has been decreased in luminance, whileedges for each icon have been preserved. Internal edge features for eachicon have also been maintained to increase recognition information foreach icon 26. Lesser and greater alterations to the video information inbackground 28 may be used.

Notably, the present invention conserves power without substantiallycompromising usability of electronics device 20. More specifically, thevideo information is altered such that the person may still see icons 26and toolbars 30 in display area 23. Thus, a user may still perceivevisual information relevant for interaction after returning to thedisplay after a period of non-usage.

In another embodiment, a program has been opened in display area 23 ofdevice 20. The program may correspond to a word processing program, forexample. During usage, the word processing program dominates displayarea 23 such that the majority of video information output by displaydevice 22 includes video information for the word processing program.For example, the word processing video information may constitute 80+%of the video information output in display area 23. In this case, powerconservation alters the video information in display area, which leavesthe toolbars 30 and headers of the word processing video program stillvisible and detectable after the alterations, but conserves the majorityof power output for display device 22. In this case, for example, a usermay still see the clock in toolbar 30 b.

Having discussed video information preservation and exemplary graphics,power conservation will now be expanded upon.

The present invention may implement a wide array of video alterations toconserve power. In general, the alteration reduces the amount of powerthat would be required to display the altered video information relativeto the video information without the alteration. Alterations may varyaccording to the video information, time, usage of the electronicsdevice, the display device and its power consumption characteristics,etc.

In one embodiment, video alteration occurs based on user activity—orlack thereof. Activity may comprise a) user input within a perimeter orouter boundary for a window for a program—as determined by the programassociated with the window, b) program output to the user—as determinedby the program, and/or c) user input in the background 48 or interactionwith the graphics-based user interface 42.

Interaction that qualifies as activity is related to one or moreprograms being output, and may vary with power conservation systemdesign. For example, user input and activity for a word processingprogram running on graphics component 45 of FIG. 1A may include: typingwithin the window 45, positioning a pointer within the window 45,clicking a button (e.g., using a mouse) within the window 45,manipulating menus and scrollbars within the window 45, a subset ofthese chosen by design, etc. User input for a music player programrunning on graphics component may include selecting songs to be playedor manipulating volume and other audio output features. Video output fora music player program may include temporally-varying video that changeswith the music based on program operation—without regular userinput—such as an equalizer output or a clock that counts music time as asong plays. In one embodiment of the present invention, the music playerprogram maintains an active graphics components status as a result ofthe temporally varying video output. In another embodiment, the powerconservation system is designed such that temporally varying videooutput for the music player program does not qualify as activity. Userinput for an Internet browser window may include positioning a pointerwithin the window, typing addresses, and opening links, for example. Inone embodiment, activity comprises temporally varying video outputprovided by a program whose video output intentionally varies over timewithout continued user input, such as a movie player. Video output isalso common with Internet browsers and may or may not constituteinteraction based on power conservation system design. User input forbackground 48 includes moving a pointer within background 48, selecting(‘clicking’ or ‘double clicking’) an icon 41, accessing individual itemson control bar 43, etc.

Inactivity for a graphics component or window implies a lack ofinteraction in the window. As activity described above depends on aprogram associated with the window, so does inactivity. In oneembodiment, inactivity is defined for an individual window according toa lack of activity for the window, which will depend on the programassociated with the window. Thus, inactivity for word processing window45 includes a lack of typing within the window boundary, a lack ofpositioning a pointer within the window boundary, a lack of manipulatingmenus and scrollbars within the window boundary, etc. Inactivity forbackground 48 may include a lack of positioning a pointer within thebackground 48 perimeter, a lack of initiating icons and menus, etc.

In one embodiment, the power conservation methods use a thresholdinactivity time to determine when alterations to video informationbegin. The power conservation methods may alternatively alter videoinformation immediately with inactivity in the display area. A user mayset the threshold inactivity time via a graphics control. Once thethreshold inactivity time has been reached, output power for the displaydevice decreases according to one or more video manipulation techniquesand the display device type.

In one embodiment, after the threshold inactivity time, videoalterations and power conservation may continue at set power reductionintervals. The power reduction intervals determine specific times afterthe threshold inactivity time at which further video alterations areapplied. This allows the altering video information to graduallychange—and power conservation to gradually increase—over time andaccording to varying design or user preference. A user may set the powerreduction intervals using a graphics control. In order for a powerreduction interval to be met, inactivity continues in the display areaor window for the duration of the interval. The threshold inactivitytime and power reduction intervals are a matter of system design anduser choice and may be different time periods.

Once the threshold inactivity time has past, the present inventionalters video information such that a display device will consume lesspower. In addition, video information other than the edge detectionvideo information may continue to adapt as time proceeds to furtherreduce power consumption. An array of video manipulation techniques maybe employed by the present invention to reduce power consumption.

Power conservation as shown in FIG. 1B reduces luminance for videoinformation other than the edge detection video information 45 a. In oneembodiment, the present invention reduces the luminance for all pixelsother than the edge detection video information by the same amount. Inother words, the altered video information becomes darker by subtractinga constant value from the luminance value for each pixel. Thiseffectively shifts a luminance histogram for the altered videoinformation to a darker state. Such a luminance reduction may beimplemented at a threshold inactivity time and at each power reductioninterval. The constant value may include a function of i) a maximumluminance for the video information other than the edge detection videoinformation (such as a percentage), ii) a maximum luminance provided bythe display device, iii) a mean, median or mode of luminance values forthe video information other than the edge detection video information,or iv) a mean, median or mode of a luminance range values provided bythe display device, etc. A suitable percentage of the maximum luminancefor the video information other than the edge detection videoinformation may range from about 2 percent to about 100 percent of themaximum luminance. Thus, a 100 percent reduction turns video informationblack at the threshold inactivity time and maximizes energyconservation. A 5 percent luminance reduction at the thresholdinactivity time and each power reduction interval thereafter steadilydecreases luminance over time. Values less than 1 percent may be usedfor subtle and/or high frequency changes. While saving less power than afull 100 percent reduction, smaller alterations may be preferable tosome users who prefer a less dramatic visual change. It is alsounderstood that the percentage reduction at the threshold activity timeand each power reduction interval may be different levels. For example,a 5 percent luminance reduction may be implemented at the thresholdinactivity time, while a 2 percent, 10 percent, or escalating (0.25,0.5, 1, 2, 4, 6, 8, 10 percent, etc.) reduction may be used at eachpower reduction interval.

In one aspect, the present invention builds a histogram for a set ofpixels being altered and reduces power consumption for the pixels usingone or more histogram-manipulation techniques. The histogram is afunction showing, for each pixel value (e.g., luminance or chroma), thenumber of pixels in an image that have that pixel value. One embodimentalters pixel values by compressing and shifting a luminance histogram.More specifically, a luminance histogram is first constructed for a setof pixels to be altered. The luminance histogram is then compressed,e.g., about the mean, median or mode. A shift subsequently reduces theluminance values for all pixels in the compressed set by a constant. Onesuitable constant is a number that gives a pixel with the lowestluminance value in the new compressed histogram a zero luminance. Thealtered video information becomes darker since the final histogramluminance varies from zero luminance to a new maximum luminance producedas a result of the compression and shift.

A suitable amount of luminance compression may range from about 1percent to about 50 percent of histogram luminance range. Anothersuitable compression may range from about 5 percent to about 20 percentof histogram luminance range. Compression and shifting may occur at thethreshold inactivity time and at each power reduction interval, ifdesired. This process may repeat at subsequent power reduction intervalsuntil the video information other than the edge detection videoinformation is almost black or until a predetermined cutoff is reached.Suitable cutoffs include: when the maximum luminance value other thanthe edge detection video information reaches a predetermined minimumluminance, when the histogram reaches a minimum width, when thedifference between subsequent iterations is minimal, or when a minimumthreshold border between the edge detection video information andaltering video information has been reached.

The present invention may implement other compression and shift schemes.In one embodiment, the luminance histogram for a set of pixels iscompressed only on one side, e.g., on the high end. If the histogramcompression occurs just on the high end, the video information becomesdarker for brighter pixels only. If the histogram compression occursonly on the low end of luminance values and then a shift is applied, thevideo information becomes darker for all pixels.

Although the present invention has primarily been discussed so far withlinear and simple reductions in luminance for pixel values in aninactive portion, a power conservation system designer may apply morecomplicated video alteration and power conservation schemes. Therelationship between power reduction, video alterations, and time may beestablished according to system design. One suitable power conservationscheme applies stepwise reductions of predetermined values atpredetermined times. Another power conservation scheme employs anexponential decrease in luminance values as time proceeds. In this case,luminance reduction starts slowly in an initial time span, increasesgradually in some midpoint time span, and then increases sharply in alater time span. A linear reduction based on y=F(x²), where y is acurrent luminance reduction, x represents the ith alteration in a numberof alterations over time, and F(x²) is some function that increasespower conservation as inactivity time passes or increases exponentiallywith a number of alterations to the video information. Linear constantsand other mathematical operators may be inserted into the equation toalter video alterations as desired. Logic may also be applied in thevideo information manipulation to achieve a desired luminance vs. timecurve.

Logic that limits further alterations to video information in subsequentpower reduction intervals may also be implemented. At this point, theentire display area may be turned off. One suitable logic applies alower limit that values of individual pixels other than the edgedetection video information may be reduced to, such as a percentage ofan initial luminance or chroma level. For example, luminance reductionsmay cease for a pixel once the pixel reaches from about 5 percent toabout 50 percent of its initial level—regardless of how it reached thispoint. Time may also be used. For example, all video information otherthan the edge detection video information may be turned off or turnedblack at a predetermined time. In addition, the entire display area,including the edge detection video information, may be turned off atsome second predetermined shut-off time.

In another embodiment, luminance reduction occurs gradually over time atsmaller intermittent time intervals (e.g., less than a minute) and smallluminance alterations, as opposed to larger and less frequentalterations. This technique provides a more gradual power reductionwithout sharp or noticeable changes in video content. For example,luminance in an inactive portion may decrease 1 percent every 10seconds, thereby decreasing luminance by 60 percent over ten minuteswithout a large and obvious single change.

Advantageously, the present invention permits more aggressivealterations and power conservation, if desired, to video informationother than the edge detection video information since the videoinformation being altered is often needed less by a user upon return tothe device after inactivity.

In another embodiment, white video information is altered. This powerconservation technique divides video information into white andnon-white video information. ‘White video information’ refers to videoinformation that has passed some threshold or criteria of whiteness. Apower conservation system designer and/or user may define a whitethreshold—and thus specify what information is altered for white powerconservation. Altering white video information to reduce powerconsumption may include reducing one or more RGB values for the whitevideo information. This produces colors and shades that are ‘off-white’,or non-Full White. A ‘replacement’ shade of white (that consumes lesspower) may be used, such as Snow White (255-250-250), Ghost White(248-248-255), Floral White (255-250-240), White Smoke (245-245-245), orOld Lace (253-245-230).

Having discussed exemplary graphics, video information preservation andvideo information alterations, video information representation andhardware power conservation will now be described in further detail. Ingeneral, video information alterations may include any changes to videoinformation that decrease power consumption, and are not limited to anyparticular color scheme used by the hardware or by the software thatimplements power conservation.

Red, green, blue (RGB) color schemes are popular and suitable tocharacterize video information according to combinations of red, greenand blue values. Video information is often stored according to an RGBscheme, while many display devices employ an RGB color scheme for videooutput. These display devices include a red, green, and blue opticalmodulation element for each pixel, such as individual RGB light emittingdiode emitters for an OLED display device, individual RGB filters for anLCD device, or a digital micromirror element used in a projector thatsequentially and selectively reflects incident red, green and blue lightfrom a lamp and color wheel into a projection lens. In many RGB baseddevices, individual optical modulation elements receive commands forvideo output that include RGB values between 0 and 255 to produce adesired video output for a pixel. For example, one greenish color mayinitially comprise red/green/blue values of 45/251/62. According toluminance reduction techniques described above, the color may bedarkened to 3/155/16, and subsequently darkened again to 2/90/9 (thismaintains the relatively same hue for the greenish color).

In one embodiment, the present invention converts data to an HSL schemeand performs video alteration in the luminance domain. Converting RGBvideo information to and from HSL video information provides a simplerforum to implement luminance control. In a specific embodiment, thepresent invention sacrifices minor changes in color quality whenperforming luminance manipulation to achieve luminance targets andtailor video alteration changes. Depending on the size of the displaydevice, the human eye generally detects changes in luminance morereadily than changes in color. While the human eye can differentiateabout 10 million colors, this level of differentiation is usuallyachieved by making side-by-side comparisons. The human eye can onlyidentify about 300 different colors from memory. Luminance and luminancedifferences are often more detectable, but vary with size of the image.

Video information alterations may be applied in a number of colorschemes, as one of skill in the art will appreciate. An HSL color schemecharacterizes video output according to a wavelength or color (hue),degree of purity of the color—or degree of separation from gray havingthe same color (saturation), and degree of brightness for the colorranging from black to white (luminance). Cyan, magenta, yellow and black(CMYK) is another color scheme regularly used to characterize videooutput from display device according to combinations of cyan, magenta,yellow and black values. In general, power conservation techniquesdescribed herein may be implemented regardless of the color scheme usedto store the video information or employed by a graphics-based userinterface, video controller or display device. Alterations and videoconservation as described herein may also apply to black and white videooutput.

Translation between the color schemes is well known to one of skill inthe art. Thus, power conservation techniques described herein may beprogrammed or stored according to one color scheme, and output accordingto another color scheme for the display device. For example, video datamanipulation techniques described herein may be implemented and storedin an HSL scheme, and then converted to and output by an RGB baseddisplay device.

Hardware power consumption and conservation will vary with displaytechnology for the display device.

OLED display devices provide pixel granularity power consumption—andpermit pixel granularity power conservation. OLED devices include a red,green, and blue individual light emitting diode or filter for eachpixel. The amount of current sent to each light emitting diode or filterincreases with each RGB color level between 0 and 255. Decreasing theRGB levels then reduces the amount of power for each diode and pixel.More specifically, altering white video information RGB values of255/255/255 to a white shade of 235/235/235 reduces the amount ofcurrent sent to each individual light emitting diode for each pixel thatemits the white shade. The amount of power conserved over the displayarea for the OLED display device can then be determined by summing thepower saved for all pixels in the display area that have been altered.

LCD display device power consumption and conservation typically relatesto backlight luminance. LCD devices provide two degrees of freedom forcontrolling luminance: 1) different luminance levels provided abacklight and 2) graduated filtering by optical modulation elements foreach pixel. FIG. 3 shows video information alteration for an exemplarypixel for an LCD device to achieve power conservation. Four luminancestates 100 a-d are shown at three different times: t=0, t=1 and t=2.

Scale 102 illustrates a number of backlight luminance levels 103 offeredby a backlight used in an LCD device. As shown, the LCD provides tendiscrete backlight levels 103, numbered from 0 to 10, where 0 is off and10 represents the maximum luminance for the backlight. In thissimplified example, each increasing integer luminance level between 0and 10 provides a proportionate increasing luminance (each levelrepresents about 10% the maximum luminance) for the backlight. Morecomplicated backlight levels are contemplated and suitable for use.

Transmissivity refers to the amount of light passage provided by opticalmodulation elements for a pixel. Many LCD devices include red green andblue (RGB) filters that act as optical modulation elements, where eachfilter regulates passage of white light produced by the backlightthrough a colored filter element to produce red, green and blue light,respectively. Transmissivity may then be expressed using RGB values senton control signals to each RGB filter. LCD devices including modulationelements that respond to RGB transmissivity values ranging from 0 to 255are common. The video information and transmissivity may also beexpressed and converted from another video data scheme, such as HSLluminance. For example, luminance for each pixel may be provided atintegers between 0 and 240, where zero represents black (full filteringand blocking of light provided by the backlight for each RGB filter) and240 represents white (no filtering and blocking of light provided by thebacklight).

As the term is used herein, ‘aggregate luminance’ refers to a luminanceoutput to a viewer of an LCD device. This aggregate luminance combinesluminance effects provided by a) the backlight and b) filtering providedby the optical modulation elements for each pixel. The aggregateluminance is typically limited to a maximum determined by the backlightlevel since the pixelated filters only reduce light currently offered bythe backlight. For FIG. 3, maximum luminance for the LCD devicecorresponds to a backlight level of 10 and luminance transmissivity of240. At backlight luminance level 9, the maximum aggregate luminance forvideo data corresponds to a luminance transmissivity of 240 (t=2).Aggregate luminance for the pixel is designated as 104 a-d for FIG. 3 ateach time instance.

Both the backlight level and the luminance transmissivity arecontrollable. In one embodiment, LCD power conservation leverages thetwo degrees of freedom in luminance control to reduce power for the LCDdevice.

At time t=0, the illustrated high luminance pixel (a white pixel)includes a backlight level of 10 and luminance transmissivity of 240,which corresponds to a maximum for the aggregate luminance and isdesignated as 104 a.

LCD power conservation alters video information for the pixel. Thisreduces transmissivity and luminance for the pixel and/or the backlightlevel. For the example at time t=1, the backlight level remains at level10 but the video information is altered to reduce the luminancetransmissivity to 228. This provides an aggregate luminance of 104 b (aless white shade). In this case, information has been altered butwithout a backlight change, and no power conservation has yet beenachieved.

At time t=2, the backlight level still remains at level 10 but the videoinformation is altered to reduce the luminance transmissivity to 216 (aneven less white shade). This provides an aggregate luminance of 104 c.Aggregate luminance of 104 c is noteworthy because it approximatelycorresponds to the aggregate luminance of 104 d provided by the LCDdevice for the pixel when the backlight level drops to level 9 and theluminance transmissivity returns to 240 (its original level). At thisluminance, the backlight level may drop from level 10 to level 9 and theluminance transmissivity increases from 216 to 240—without changing theaggregate luminance of 104 output to the viewer—or as perceived by aviewer. Thus, a person may not notice the backlight change. Powerconsumption for the backlight and LCD device reduces when the backlightlevel changes from level 10 to level 9.

For an LCD, aggregate luminance is then manipulated for all pixelsaffected by a backlight (some LCD devices include more than one). Videoinformation for the image is altered to produce a new maximum luminancethat is less than the next or largest available luminance at the nextbacklight level. Then, the LCD switches to the next backlight level.

Although the above example has been simplified to illustrate two degreeof freedom luminance control and power conservation using and LCD, powerconservation as described herein is not limited to such simpleexpressions of backlit luminance levels and pixel transmissivity. Theabove example employed ten backlight luminance levels; other numbers ofbacklight luminance levels are contemplated. In general, the LCD devicemay include any number of backlight luminance levels. As the granularityof backlit luminance levels increases, so does power conservation andthe ability to more readily use a lower backlight level. The backlightluminance levels also need not correspond to simple fractions of themaximum luminance or integer levels as described above. In addition,luminance transmissivity is not limited to expression using a range of1-240. Other luminance transmissivity and color schemes, such asnormalized scales, are also suitable for use. As one of skill in the artwill appreciate, the number and characterization of backlight luminancelevels will depend on the LCD used, while the number andcharacterization of video information will depend on the video schemeused to represent the video data.

Aggregate luminance thus allows a designer to relate backlight luminancelevels and pixel transmissivity for an LCD device, which permits adesigner to alter the video information and direct the modificationstowards backlight luminance reductions. An aggregate luminance model maybe built for a device that estimates luminance perceived by a user as acombination of backlight and pixilated transmissivity. For example, theaggregate luminance may be used to provide a ratio (or another suitablemathematical relationship) between the backlight luminance levels andpixel transmissivity.

One video alteration embodiment for LCD use sets a high luminance limitfor a histogram of luminance after an alteration. The high luminancelimit refers to a reference luminance level for video information in thedisplay area that may be used to guide alteration, e.g., before changinga next backlight luminance on an LCD device. The edge detection videoinformation may rest near the high luminance limit, while the remainingvideo information other than the edge detection video information isaltered to a lesser aggregate luminance. This maintains visible salienceof the edge detection video information relative to the remaining videoinformation, and allows stepwise decreases in backlight luminance. Thisalso allows luminance for any pixel in the image to remain relativelyconstant at the moment of each backlight level change (to produce littleperceptible change). Further description of LCD based power conservationsuitable for use with the present invention is described in commonlyowned pending patent application Ser. No. 11/122,313 and entitled “LCDPlateau Power Conservation”, which is incorporated herein in itsentirety for all purposes.

FIG. 4A illustrates a process flow 200 for reducing power consumed by anelectronics device and/or display device in accordance with oneembodiment of the invention. While the present invention will now bedescribed as a method and separable actions for reducing powerconsumption, those skilled in the art will recognize that the subsequentdescription may also illustrate hardware and/or software systems anditems capable of performing the method and actions.

Process flow 200 begins by generating edge detection video informationfor a graphics component (202). Generation may vary based on thegraphics component, graphical user interface, etc. In general, the edgedetection video information allows a person to visually locate thegraphics component in a display area for the display device. In oneembodiment, a power conservation program run on the electronics deviceautomatically identifies the edge detection video information for eachgraphics component according to system design. In another embodiment, auser toggles this functionality using a power conservation graphicscontrol offered by a graphical user interface. The graphics control mayalso permit user input regarding what edge detection video informationis preserved (e.g., perimeter information, internal information, color,text, etc.).

Generation (202) may employ edge designation logic and/or one or moreedge detection algorithms to determine the edge detection videoinformation—and what video information to preserve to maintain aperson's ability to locate and identify the graphics component.

The edge designation logic operates on a series of stored instructionsthat determine edge detection video information for a graphicscomponent. The edge designation logic may define perimeter informationusing visual boundaries of a graphics component, for example. For FIG.1A for example, the edge designation logic processes each icon 41 andprovides an outer contour for each icon 41. Many icons have a uniqueshape, or visual information that can generate a distinguishable shape(such as a circle for a globe icon, an ‘e’ for an Internet icon, a fileshape for a file icon, etc., see FIG. 2B for more icon shapes as well).In addition, the predetermined edge designation logic provides the edgedetection video information for the toolbar 43 of FIG. 1A and how itwill appear when power conservation occurs (e.g., a rectangle isprovided for each toggle). Since these graphics components arerelatively stable in location and size in a display area, thepredetermined edge designation logic then reliably provides consistentedge representations of these graphics components that do not changesignificantly over time. In this case, the edge detection videoinformation for one or more icons, toolbar or other temporallyconsistent graphics components may be stored for ready use when powerconservation begins.

The edge designation logic may also provide edge detection videoinformation for the program windows 45 and 47, which may change in sizeand location. In this case, the logic adjusts for the varying locationand size of each window, and generates perimeter edge detection videoinformation for each window based on the current position and size ofeach window, accordingly, at the time of power conservation initiation.The perimeter edge detection video information may include only pixelsfor the outermost edge of each window. In another embodiment, theperimeter video information for each window includes a multiple pixelthickness (e.g., 2-6 pixels).

Generation (202) may also include instructions that access a storedrepresentation of a graphics component to generate the perimeter and/orinternal edge detection video information from the storedrepresentation.

In another embodiment, generation (202) employs one or more automatededge detection techniques. These are useful for graphics components thatdo not readily include characteristic perimeter information in a storedbitmap, for example. The edge detection techniques are used to buildperimeter or shape detection video information for any videodata—whether or not the video information is included in a separategraphics component bitmap. In this case, a shape detection algorithm ortool probes video information in an image according to one or more edgedetection, contour tracing and shape measurement techniques andconstructs perimeter information for the graphics component. Some commonedge detection techniques (or filters) include a Robert's Gradient,Sobel masks, Prewitt masks, Kirsh masks, LaPlacian filters, isotropic(e.g., horizontal and vertical) border extractions, etc. Edge detectiontechniques are known to those of skill in the art. Different weights andthresholds may also be used at each location in an edge filter,depending on the image and desired sharpness of the output edgedetection information. After edge detection is complete, the presentinvention may then alter video information for the graphics componentbased on the results of the edge detection. In general, the presentinvention may employ any suitable gradient algorithm or filter thatidentifies an edge for a graphics component.

The edge detection techniques may also employ one or more smoothingoperations to clean video information in an image and reduce noise inthe display area to prepare the video information better for an edgedetection algorithm. For example, a Gaussian filter may be used to firstclean noise in the video information before performing an edgedetection. Other smoothing techniques and algorithms may be used.

The output of generation 202 may include a continuous curve of pixellocations that is represented and stored as a sequence of points, or acontour.

Process flow 200 then proceeds by altering the video information outother than the edge detection video information (204). The videoinformation is altered such that the display device will consume lesspower when displaying the altered video information than an amount ofpower that would be required to display the video information withoutthe alteration.

In a specific embodiment, video information alters immediately uponinactivity in the display area. One suitable luminance reduction schemedecreases luminance incrementally and alters video information at powerreduction intervals that begin immediately upon user inactivity and havea frequency of greater than 1 alteration every 5 seconds. In this case,the incremental reductions decrease luminance by a tiny amount each timesuch that any individual alteration is not readily noticeable to a user.Cumulatively, however, the incremental alterations may accumulate toproduce a significant change, such as a 50 percent reduction inluminance for the background and graphics components over five minutesfor example. The gradual rate of alteration may be established accordingto power conservation system design or user preference, andadvantageously allows video information to alter without substantiallynoticeable momentous changes. A magnitude for each incrementalalteration may be determined by dividing a desired total alteration overa period of time by the number of intervals in the time period. Forexample, the progressive changes may occur as often as desired toproduce a backlight luminance level change in an LCD device every 30seconds. The backlight luminance level change may then occur withoutchanging aggregate luminance perceived by a user.

The altered video information and edge detection video information arethen displayed together on the display device (206). One of skill in theart is aware that there are multiple techniques to display edgeinformation or a display area that includes edge detection videoinformation. In one embodiment, video information in the display area isonly shown when it passes an edge detection threshold; information thatdoes not pass the threshold is then displayed with decreased luminance,or black. In another embodiment, additional steps may be taken to reducesmearing when displaying the altered video information with the edgedetection video information.

In one embodiment, edge detection video information is superimposed ontodarkened video information to highlight relatively lighter edgesincluded in the edge detection video information. In this case, allvideo information adjacent to the edges is decreased in luminance tohelp locate the edges. For example, all video information in the displayarea, other than the edge detection video information, is darkened andthe edge information superimposed onto the darkened video information.For an OLED, this will save power for each pixel so converted—andconsiderable for the display area and electronics device.

FIG. 4B illustrates a process flow 210 for reducing power consumed by anelectronics device and/or display device in accordance with anotherembodiment of the invention. Process flow 210 begins by setting a powerconservation scheme (211). A power scheme refers to a collection ofpower options that dictate how and when video information is altered toreduce power consumption. In one embodiment, a power conservation systemis stored on a computer and implements a power conservation schemewithout user input (including generation of the edge detection videoinformation, 202). In another embodiment, a graphics control allows auser to set a power scheme or one or more power options corresponding totechniques described herein, e.g., the user helps designate and generatethe edge detection video information (202).

For process flow 210, the power conservation scheme uses a thresholdinactivity time to determine when alterations to video data begin. Thethreshold inactivity time may beset by a user via a graphics control, orautomatically with power conservation system design. Once the thresholdinactivity time has been reached, video information is altered to reducepower consumption.

After the power conservation scheme has been established, process flow200 monitors user activity within the display area (213). Process flow210 continues to monitor activity over time and reacts according to anyuser activity or lack thereof (216). If user activity occurs in thedisplay area, process flow 210 then resets the inactivity monitor clockand returns to 213. If user inactivity continues until the thresholdinactivity time, then process flow 210 alters video information.

For process flow 210, video information for the edge detection videoinformation is also altered. In this case, alterations to the edgedetection video information occur at a lesser rate than that for othervideo information. Process flow 200 proceeds by altering the videoinformation for the edge detection video information at a first rate(220). The change may include reducing the luminance for the edgedetection video information such that a next luminance level in an LCDdevice may be employed.

Power conservation also alters the video information other than the edgedetection video information (204). Luminance may be reduced so as toincrease contrast between the altered video information and the edgedetection video information, which increases visibility of the edgedetection video information. For an OLED device, since the edgedetection video information occupies a minor amount of space, thisalteration (204) leads to the majority of power conservation. Suitabletechniques for altering video information other than the edge detectionvideo information were described above.

In one embodiment, the video information is altered such that a minimumthreshold detection border is at least maintained between the edgedetection video information and the altered video information. Thus,both the edge detection video information and other altered videoinformation are adapted to maintain visible step boundaries between atthe edge detection video information.

In this duel alteration embodiment, the video information for the edgedetection video information alters at a lesser rate than the videoinformation other than the edge detection video information. In onetemporally varying embodiment, alterations to video information occur atset power reduction intervals. The power reduction intervals determinespecific regular times at which minor but additive video alterations areapplied. In this case, alterations to the edge detection videoinformation may occur less frequently (at larger intervals) than forvideo information other than the edge detection video information. Forexample, progressive and stepwise changes to RGB values of the formermay occur every twenty seconds while progressive and stepwise changes toRGB values of the latter may occur every ten seconds. Other intervalsmay be used. In one embodiment, a power reduction interval from onesecond to about 3 minutes is suitable. In another embodiment, a powerreduction interval from about 1 second to about 10 seconds is suitable.It is understood that power reduction intervals are a matter of systemdesign and user choice and may be include different time periods thatthose specifically provided herein.

The difference in rate of alteration may also include changes at thesame frequency—but by different amounts at each interval. In this case,video information other than the edge detection video information isaltered more aggressively at each interval than that of the edgedetection video information.

Altered video information returns—or reactivates—to its original statefrom an altered state after user activity with the display area, or asotherwise designated by a power conservation program designer.Reactivation displays the display area as it was initially displayedbefore any alterations. In a specific embodiment, positioning a pointeronto an area of a display area triggers reactivation. Reactivation mayalso include initiating a window via its corresponding toggle on toolbar43. Power conservation system designers may also customize reactivationrules. For example, reactivation may be designed such that solelypositioning and moving a pointer within a window or background does notsatisfy reactivation criteria. In this case, clicking a button on amouse while the pointer is within the window, or another explicit actionwithin the graphics component, may satisfy reactivation.

In another embodiment, inactivity within the display area may bemonitored and timed. The graphics-based user interface may include aglobal power saving tool that initiates after a predetermined time ofinactivity throughout the entire display area. In this case, the globalpower saving tool turns off video display for the entire display area,including the edge detection video information being preserved, wheninactivity reaches the global power saving tool time limit, e.g., suchas 5 minutes.

In one embodiment, power conservation as described herein is implementedwithout user input. In another embodiment, a computer system provides auser the ability to turn on/off power conservation or tailor the powerconservation to personal preferences that include the ability toidentify edge detection video information for a window.

The present invention may also include controls for implementing powerconservation. Graphics-based user interfaces employ what are referred toas graphics “controls”. A graphics control is a discrete video object,for display by a display device, which can be manipulated by a user toalter one or more graphics outputs or effects and/or to initiate anaction in an the graphical user interface. The graphics control oftenincludes its own bitmap comprising an array of pixel values. For thepresent invention, the graphics control includes visual tools that allowa user to turn on/off visual preservation for edge detection videoinformation in general, and/or identify edge detection video informationfor a window. Further description of graphics controls suitable for usewith the present invention is provided in commonly owned U.S. patentapplication Ser. No. 10/891,734, which was incorporated by referenceabove.

The present invention may also relate to systems for reducing powerconsumed by a display device. The power conservation system may compriseany combination of software and hardware for carrying out actionsdescribed herein. In a specific embodiment, general-purpose computerprocessing units, instead of dedicated hardware, implement themonitoring and video alteration techniques. Further description of powerconservation systems suitable for use with the present invention isprovided in commonly owned U.S. patent application Ser. No. 10/891,734,which was incorporated by reference above.

The present invention finds use with computer systems such as desktopand laptop computers, personal digital assistants (PDAs), cellulartelephones, digital cameras, portable computer systems, and the like.FIG. 5 schematically illustrates an exemplary general-purpose computersystem 300 suitable for implementing the present invention.

Computer system 300 comprises a processor, or CPU, 302, one or morememories 314 and 316, input/output (I/O) circuitry 306, display device308, input device 310, and system bus 312. System bus 312 permitsdigital communication between system processor 302 and ROM 314, as wellas permits communication between other components within system 300 andprocessor 302 and/or ROM 314.

System 300 memory includes read only memory (ROM) 314 and random accessmemory (RAM) 316. Other memories may be included. ROM 314 stores a basicinput/output system 318 (BIOS), containing basic routines that help totransfer information between elements within computer system 300, suchas during start-up. Computer system 300 may also include a hard diskdrive and an optical disk drive, for example. The optical disk drivereads from and may write to a CD-ROM disk or other optical media. Thedrives and their associated computer-readable media provide non-volatilestorage for system 300. A number of program modules may be stored in thedrives, ROM 314, and/or RAM 316, including an operating system, one ormore application programs, other program modules, and program data.Although data storage above refers to a hard disk and optical disk,those skilled in the art will appreciate that other types of storage aresuitable for use with a computer system, such as magnetic cassettes,flash memory cards, USB memory sticks, and the like. In addition, notall computer systems, such as PDAs and other portable devices mayinclude multiple external memory options.

Processor 302 is a commercially available microprocessor such as one ofthe Intel or Motorola family of chips, or another suitable commerciallyavailable processor. Processor 302 digitally communicates with ROM 314via system bus 312, which may comprise a data bus, control bus, andaddress bus for communication between processor 302 and memory 314. CPU302 is also coupled to the I/O circuitry 306 by system bus 312 to permitdata transfers with peripheral devices.

I/O circuitry 306 provides an interface between CPU 302 and suchperipheral devices as display device 308, input device 310, audio output334 and/or any other I/O device. For example, a mouse used as inputdevice 310 may digitally communicate with processor 302 through a serialport 306 that is coupled to system bus 312. Other interfaces, such as agame port, a universal serial bus (USB) or fire wire, may also providedigital communication between a peripheral device and processor 302. I/Ocircuitry 306 may also include latches, registers and direct memoryaccess (DMA) controllers employed for interface with peripheral andother devices. Audio output 334 may comprise one or more speakersemployed by a headphone or speaker system.

Display device 308 outputs video information—both unaltered andaltered—including graphics components, backgrounds, graphics controlssuch as those described herein, graphics-based user interfaces, andother visual representations of data. For example, display device 308may comprise a cathode ray tube (CRT), liquid crystal display (LCD),organic light emitting diode (OLED), or plasma display, of the typescommercially available from a variety of manufacturers. Display device308 may also comprise one or more optical modulation devices, or thelike, used in projecting an image. Projection display devices thatproject an image onto a receiving surface are becoming more popular,less expensive, more compact; and may employ one or more opticalmodulation technologies as well as a wide variety of individual designs.Common optical modulation devices include those employing liquid crystaldisplay (LCD) technology and digital mirror device (DMD) technology.When used as a display device for a computer, these projection devicesprovide the potential for a much larger image size and user interface.In general, the present invention is not limited to use with anyparticular display device.

The present invention is independent of any particular display device,any mechanism of light generation for a display device, or any powerconsumption scheme for a display device, and only assumes that powerconsumption for display device 158 may vary with video information. In aspecific embodiment, display device 158 can vary power consumptionspatially on a pixel-by-pixel basis.

Display device 308 may also digitally communicate with system bus 306via a separate video interface, such as a video adapter 346. Videoadapter 346 is responsible for assisting processor 302 with videographics processing including power conservation alterations describedherein. Video adapter 346 may be a separate graphics card or graphicsprocessor available from a variety of vendors that are well known in theart.

Input device 310 allows a user to enter commands and information intothe computer system 300, and may comprise a keyboard, a mouse, aposition-sensing pad on a laptop computer, a stylus working incooperation with a position-sensing display on a PDA, or the like. Otherinput devices may include a remote control (for a projector),microphone, joystick, game pad, scanner, or the like. As used herein,input device refers to any mechanism or device for entering data and/orpointing to a particular location on an image of a computer display.Input as described herein may also come through intermediary devices.For example, a remote control may communicate directly with processor302, or through an intermediary processor included in another devicesuch as a hybrid entertainment device such as a set-top box orprojector. The user may then input information to computer system 300using an infrared remote control device that communicates first with theintermediary device, and then to processor 302.

In one embodiment, a graphics-based user interface implemented bycomputer system 300 displays a graphics control such as controldescribed above. To display a power conservation graphics control,processor 302 issues an appropriate command, followed by anidentification of data that is to be used to construct the graphicscontrol. Such data may include a number of power conservation controltools that allow a user to change how video data is altered. ROM 314also stores a number power conservation commands and instructions forimplementing the techniques described herein. In one embodiment, thepresent invention is practiced in the context of an application programthat runs on an operating system implemented by computer system 300 orin combination with other program modules on computer system 300.

The present invention may be implemented on a range of computer systems.In addition to personal computers such as desktop computers and laptopcomputers, a variety of other computer systems and computer devicesemploying a digital processor, memory and a display device may implementthe present invention. Handheld computers and other small portabledigital devices such as cell phones and digital cameras are increasinglyintegrating video display and computer functionality. One current trendis hybrid entertainment devices that integrate the functionality ofcomputer systems, audio devices, and televisions. Any of these devicesmay employ and benefit from the power conservation methods and systemsdescribed herein. The scope of digital computer systems is expandinghurriedly and creating new devices that may employ the presentinvention. In general, any digital device employing an output displaydevice that varies output power with video content may benefit from thepresent invention. Moreover, those skilled in the art will appreciatethat the invention may be practiced with other computer systemconfigurations, multiple display device systems, multi-processorsystems, microprocessor-based or programmable consumer electronics,minicomputers, mainframe computers, and the like.

The present invention is particularly useful to portable computingdevices run with battery power. Most handheld devices are designed torely on battery power. In addition, although the present invention hasbeen discussed with respect to reduced power consumption, energy andpower are relatively interchangeable in a discussion of the benefits ofconservation.

Embodiments of the present invention further relate to computer readablemedia that include program instructions for performing powerconservation techniques described herein. The media and programinstructions may be those specially designed and constructed for thepurposes of the present invention, or any kind well known and availableto those having skill in the computer software arts. Examples ofcomputer-readable media include, but are not limited to, magnetic mediasuch as hard disks, semiconductor memory, optical media such as CD-ROMdisks; magneto-optical media such as optical disks; and hardware devicesthat are specially configured to store program instructions, such asread-only memory devices (ROM), flash memory devices, EEPROMs, EPROMs,etc. and random access memory (RAM). Examples of program instructionsinclude both machine code, such as produced by a compiler, and filescontaining higher-level code that may be executed by the computer usingan interpreter.

Graphics controls and graphics-based user interfaces such as thosedescribed herein may be implemented using a number of computer languagesand in a number of programming environments. One suitable language isJava, available from Sun Microsystems of Sunnyvale, Calif. Anothersuitable programming environment is the Microsoft Windows® programmingenvironment, which provides a series of operating systems suitable forimplementing the present invention both on laptop computers and handheldcomputers.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, those skilled in the art willrecognize that various modifications may be made within the scope of theappended claims. In addition, although power consumption andconservation has not been detailed for every type of display device, thepresent invention is suitable with any display technology that can varypower output with video information. Projectors, for example, consumepower based on the amount of light produced, which may be reduced usingtechniques described herein. The invention is, therefore, not limited tothe specific features and embodiments described herein and claimed inany of its forms or modifications within the scope of the appendedclaims.

1. A method for reducing power consumed by an electronics device thatincludes a display device, the method comprising: generating edgedetection video information for a graphics component that allows aperson to visually locate the graphics component in a display area forthe display device, wherein the edge detection video informationincludes perimeter edge detection video information; altering videoinformation in the display area, wherein altering video informationincludes altering video information in an internal portion of thegraphics component that is inside the perimeter edge detection videoinformation and altering video information that is outside the perimeteredge detection video information, while visually preserving the edgedetection video information relative to the video information in theinternal portion of the graphics component and relative to the videoinformation that is outside the perimeter edge detection videoinformation, to produce altered video information, such that the displaydevice will consume less power when displaying the altered videoinformation than an amount of power that would be required to displaythe video information without the alteration; and displaying the alteredvideo information with the edge detection video information.
 2. Themethod of claim 1 wherein preserving the edge detection videoinformation includes not altering the edge detection video information.3. The method of claim 1 wherein preserving the edge detection videoinformation includes turning the edge detection video information towhite.
 4. The method of claim 2 wherein the graphics component outputsvideo information for one of: a word processing program, an InternetBrowser interface, a graphics control, a music player program, and avideo game.
 5. The method of claim 2 wherein edge detection videoinformation includes a contour of pixel locations for the graphicscomponent.
 6. The method of claim 1 wherein the edge detection videoinformation includes internal edge information that increases an amountof edge detection video information for the graphics component anddistinguishes two similarly shaped graphics components.
 7. The method ofclaim 1 wherein generating the edge detection video information useslogic to determine the edge detection video information.
 8. The methodof claim 1 wherein generating the edge detection video information usesan edge detection algorithm to determine the edge detection videoinformation.
 9. The method of claim 1 wherein the alteration comprises aluminance reduction for the video information in the display area otherthan the edge detection video information.
 10. The method of claim 9wherein the luminance reduction includes a histogram compression and ahistogram shift for the video information in the display area other thanthe edge detection video information.
 11. The method of claim 9 whereinthe luminance reduction increases contrast between the altered videoinformation and the edge detection video information.
 12. The method ofclaim 9 displaying the altered video information with the edge detectionvideo information includes superimposing the edge detection videoinformation onto the altered video information.
 13. The method of claim1 wherein further comprising a second alteration of the videoinformation in the display area other than the edge detection videoinformation.
 14. The method of claim 1 wherein the display device is anOLED device.
 15. The method of claim 1 wherein the display device isincluded in one of: a laptop computer, a handheld computer, a portablephone or a portable music player.
 16. The method of claim 1 wherein thegraphics component is one of: a rectangular window, an icon, and atoggle.
 17. A method for reducing power consumed by an electronicsdevice that includes a display device, the method comprising: generatingedge detection video information for a graphics component in a displayarea for the display device that allows a person to visually locate thegraphics component in the display area, wherein the edge detection videoinformation includes perimeter edge detection video information;monitoring user activity in the display area; after a thresholdinactivity time in the display area, wherein altering video informationincludes altering video information in an internal portion of thegraphics component that is inside the perimeter edge detection videoinformation and altering video information that is outside the perimeteredge detection video information, while visually preserving the edgedetection video information relative to the video information in theinternal portion of the graphics component and relative to the videoinformation that is outside the perimeter edge detection videoinformation, to produce altered video information, such that the displaydevice will consume less power when displaying the altered videoinformation than an amount of power that would be required to displaythe video information without the alteration; and displaying the alteredvideo information with the edge detection video information.
 18. Themethod of claim 17 wherein the alteration comprises a luminancereduction for the video information other than the edge detection videoinformation.
 19. The method of claim 17 wherein further comprising asecond alteration to the altered video information after inactivity inthe display area for a power reduction interval that follows thethreshold inactivity time.
 20. A computer readable medium includinginstructions for reducing power consumed by an electronics device thatincludes a display device, the computer-readable medium comprising:instructions for generating edge detection video information for agraphics component that allows a person to visually locate the graphicscomponent in a display area for the display device, wherein the edgedetection video information includes perimeter edge detection videoinformation; instructions for altering video information in the displayarea, wherein altering video information includes altering videoinformation in an internal portion of the graphics component that isinside the perimeter edge detection video information and altering videoinformation that is outside the perimeter edge detection videoinformation, while visually preserving the edge detection videoinformation relative to the video information in the internal portion ofthe graphics component and relative to the video information that isoutside the perimeter edge detection video information, to producealtered video information, such that the display device will consumeless power when displaying the altered video information than an amountof power that would be required to display the video information withoutthe alteration instructions for displaying the altered video informationwith the edge detection video information.